29mm and 38mm Forstner Bits

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splintered sun

Member
I like making my own centering rings and currently use a 1 and 1/4" forstner bit and then a sanding jig to fit the body tubes. The minor issue I have is the 1 and 1/4" bit is just a fraction too big for the 29mm MT so some extra epoxy is needed to hold them in place.

I found a company that sells metric bits but they only carry carbide bits in those sizes - which makes them pretty pricey ($51 and$81 respectively). I realize that carbide may be the best way to go in the long run, but does anyone know of another supplier of forstner bits in those sizes for less dough?

Handeman

Well-Known Member
TRF Supporter
not sure these will be the right size, no metric, but they are less,

McMaster-Carr catalog page 2426

I use an Adjustable Diameter Hole Cutter I got from Sears, but here one on catalog page 2369.

If you need a drill press to use the hole cutter, Grizzly has a bench top one for $120 here that would be the cost of the two bits. They also have circle cutters for$11 and $20. The$11 one has two blades so you can cut the whole CR in one swipe.

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splintered sun

Member
Thanks guys. I think i'll go the CMT bits route.

I do have a drill press but the manual states numerous times that circle cutters/fly cutters should not be used. I believe the issue is that the slowest speed I can tune the press down to is 300 rpm which may be unsafe for those types of cutters and I'm a bit of a chicken and might prefer not to risk impalement over a centering ring. .

Handeman

Well-Known Member
TRF Supporter
Actually the cutters usually state the maximum RPM is 500, or there abouts. 300 RPM should be plenty slow.

The most likely reason they say not to use cutters like that is the stress it puts on the bearings and structure of the head. It maybe more of a warrenty issue then a safety thing if it's a lower cost drill press.

RandyM

Well-Known Member
Thanks guys. I think i'll go the CMT bits route.

I do have a drill press but the manual states numerous times that circle cutters/fly cutters should not be used. I believe the issue is that the slowest speed I can tune the press down to is 300 rpm which may be unsafe for those types of cutters and I'm a bit of a chicken and might prefer not to risk impalement over a centering ring. .
You're not a chicken, just smart in my opinion. I used to use those until the day I had one loosen up while cutting a ring. The cutting blade flew off and I still have a nice scar on my arm to prove it. I ditched the drill press and bought a plunge router and a Jasper jig. Again in my opinion, it's the best (and safest) way to go.

Ez2cDave

Well-Known Member
TRF Supporter
I like making my own centering rings and currently use a 1 and 1/4" forstner bit and then a sanding jig to fit the body tubes. The minor issue I have is the 1 and 1/4" bit is just a fraction too big for the 29mm MT so some extra epoxy is needed to hold them in place.

HERE'S A THOUGHT . . .

You could take the 1.25" bit to a machine shop and have them turn it down to what ever diameter you need . . .

Dave Fitch